In alphabetical order:
Here's what Tony says about each name:
I like Killian because then we can call him Killy for short.
I like Kincaid because Caid is a cool short name. And when he gets older, "Kinky".
I like Quentin because that's my middle name and then my names are the bread in our baby name sandwich.
I like Quinn because it's a nice, short Scottish name and we both have lots of Scottish heritage. Not that we'll be putting him in kilts or getting him bagpipe lessons, but it's nice to give your child a link to their heritage.
Please note that he is joking about the nicknames "Killy" and "Kinky" :)